Current locking systems are often electronically controlled. For example, many vehicles such as cars and trucks include locking systems controlled by one or more electronic control units (ECUs), electronic control modules (ECMs), or other electronic controllers. ECU-controlled locking systems may be used, for example, to lock external vehicle doors or to control the vehicle ignition. As an illustrative example, an ECU may unlock the vehicle by sending an electrical signal to a relay that activates a lock solenoid to physically unlock the vehicle. In addition to mechanical keys, ECU-controlled locking systems may also allow remote operation through communication with a transponder key, key fob, or other device using radio frequency-based signal technologies.
Physical unclonable functions (PUFs) are electronic circuits or other electronic devices that, in response to receiving a challenge signal, generate a response signal. For example, a PUF circuit may receive a voltage signal, a power signal, or other electronic signal and generate a response voltage signal, current signal, or other electrical response. Due to manufacturing variations, the response of each PUF to the challenge signal is unique and cannot be copied in another PUF. Additionally, each PUF may include or be otherwise coupled to one or more fuses, switches, or other one-time-use devices that, when activated, modify the response of the PUF to the challenge signal.